Motor driven lamp unit and method



Aug. 14, 1962 E. c. SAWYER MOTOR DRIVEN LAMP UNIT AND'METHOD Filed March21, 1960 mdE INVENTOR. EDWARD C. SAWYER BY 4 m lL. W%& 7

ATTORNEYS atent 3,049,615 Patented Aug. 14, 1962 3,049,615 MOTOR DRIVENLAMP UNIT AND METl-Ifil) Edward C. Sawyer, 9200 River Valley, Brighton,Mich. Filed Mar. 21, 1960, Ser. No. 16,273 2 Claims. (Cl. 240-49) Thisinvention relates to a motor driven lamp unit and refers moreparticularly to a lamp unit which is particularly adapted to illuminatea large area.

In order to illuminate a large area, it has been necessary in the pastto employ several individual light units carefully arranged to cover theentire area with some degree of uniformity. At best it is possible onlyto approach a condition in which the area is lighted with uniformity,and invariably a large number of lamps are required to do the job. Thisinvolves a substantial expenditure of money both in equipment and inelectric power to operate the lamps.

One object of this invention is to provide a single power operated lampunit which is particularly adapted to illuminate an area much largerthan heretofore has been considered possible.

Another object of the invention is to provide a lamp unit having meansfor moving the lamp in cycles through a fixed path at a high rate ofspeed such that the elapsed time per cycle is on the order of the lightretention time of the normal human eye or less. As a result, the entirearea embraced by the fixed path will be flooded with light, and althoughthe illumination of any part of the path is intermittent, the speed ofthe lamp is so fast that there is no flicker or interruption inillumination apparent to the eye.

Still another object of the invention is to provide a lamp unit asdescribed above having a support provided therefore mounted forrotation, means for mounting the lamp unit on the support for pivotalmovement about an axis at right angles to and intersecting the axis ofrotation of the support, means for locking the lamp unit in selectedpositions of pivotal adjustment, and means for rotating the support andlamp unit as described above to illuminate the large area covered by therotating lamp unit.

A still further object of the invention is to provide a lamp unit asdescribed above in which the center of gravity of the lamp unit lies onthe intersection of the axis of rotation of the support and the axis forpivotal adjustment of the lamp unit, so that the lamp unit is perfectlybalanced and will not set up vibrations in the apparatus duringoperation.

Another object of the invention is to provide a lamp unit as describedabove having a hollow shell completely enclosing and rotating with thelamp unit, the outer surface of which is symmetrical with respect to theaxis of rotation of the lamp unit and its support.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings, wherein:

FIGURE 1 is a side elevational view of a motor driven lamp unit, withthe hollow shell in section, constructed in accordance with myinvention.

FIGURE 2 is a view looking down on the structure of FIGURE 1 with thehollow shell in section.

Referring now more particularly to the drawing, the lamp unit isgenerally indicated at and the support at 12. The lamp unit 10 comprisesa lamp 14 of the usual construction which can be purchased in any storehandling this particular class of goods. The lamp 14 has a casing '16which is cone shaped and closed at the front by a glass window 18, andthe electrical terminals for energizing the filaments of the lamp withinthe housing are at the small end of the lamp opposite the glass 18.

The support 12 is in the form of a yoke having the spaced upwardlyextending arms 20 and 22. The lamp unit 10 is supported by the arms ofthe yoke for pivotal adjustment in a manner more fully describedhereinafter. The lower end of the yoke is formed with a dependingextension 24 which is coupled to the hollow drive shaft 26 of motor 27by a collar 28. As seen in FIGURE 1, the extension 24 and drive shaft 26extend into opposite ends of the collar and are releasably securedthereto by set screws 30.

The motor 27 is mounted with the axis of its shaft 26 vertical. Thedrive shaft 26 as well as the supporting yoke 30 are preferably disposedvertically for rotation about their aligned axes generally indicated at42.

The lamp unit includes a generally U-shaped' mounting bracket 44, thelegs of which are secured at their ends, as by welding, to the large endof the lamp casing 16, and the portion connecting the legs of thebracket extends across the small end of the lamp and is secured thereto.A ring 46 encircles the lamp near its midpoint, and the legs of thebracket 44 have intermediate opposed parallel portions 48 which arepermanently secured to diagrammatically opposite sides of the ring 46.The legs 20 and 22 are formed with aligned apertures which register withapertures in the ring 46 and in the parallel portions 48 of the bracketlegs, and pivot studs 52 extend through the aligned apertures. The pivotstuds are aligned and define the axis for pivotal adjustment of the lampunit with respect to the supporting yoke. The axis of pivotal adjustmentis indicated by the reference numeral 54 and extends at right angles toand intersects the axis of rotation 42 of the support. The pivot studs52 are each in the form of a bolt having a head on one end and threaded0n the other to receive a wing nut 56. By tightening the wing nuts, thelamp unit may be locked in selected positions of pivotal adjustment withrespect to the axis 54. If desired, the engaging surfaces of thesupporting yoke leg 22 and the parallel portion of the bracket 44 may beserrated, that is formed with engaging radial serrations, to provide amore positive locking action when the wing nuts are tightened.

Because of the high rate at which the support 12 and lamp unit 10 arerotated, near perfect balance is required so that no vibration is setup. It will be noted that the supporting yoke 12 is symmetrical withrespect to the axis of rotation 42. Moreover, the center of gravity ofthe lamp unit 10, including the lamp 14 and its component parts, thebracket 44 and ring 46, lies on the intersection between the axis ofrotation 42 and the axis of pivotal adjustment 54. Also, the pivot studsand wing nuts are identical and in perfect balance, being equaldistances from the axis of rotation.

The lamp unit and the portion of the support above the dependingextension 24 is completely enclosed within a hollow shell sphere 60 madeof glass or other transparent material. Actually the shell need betransparent only in the front section to transmit the beam of light fromthe lamp. The sphere is made up of two half sections, the circularmarginal portion of one of which being displaced radially inwardly asshown at 62 to provide a surface to surface engagement with the marginalportion of the other. The sections of the sphere may be press fittedtogether to provide a joint sufficiently tight to withstand the stressduring rotation, or if desired, a small amount of adhesive may beemployed to secure the joint. The lower portion of the sphere isprovided with an aperture to clear the collar 28 and such lower portionis flattened in a circular area as shown at 66 to lie flat against theradial enlargement on the yoke. Fasteners 68 may be provided forremovably securing the flattened portion of the sphere sections to theradially enlarged portion of the support. The shell is of coursesymmetrical with respect to axis 42. The main purpose of the shell is tocut down on air resistance, which is an important factor at the speedsinvolved. The shell rotates with the lamp and is such that air frictionand hence power consumption are reduced. Also, there is little or notendency for whistling noises to develop during rotation.

Normally the apparatus will be set up at a high support over the area tobe illuminated with the axis of rotation 42 disposed vertically. Thelamp 18 may then be adjusted pivotally with respect to the axis ofrotation 54, and then locked in selected position by the wing nuts 56.Thereupon the sections of the sphere are assembled in position andsecured to the support to rotate as a unit therewith. The motor 40 isthen operated to drive the shaft 26 and lamp unit at a high rate ofspeed. The lamp unit is rotated at a speed such that the elapsed timeper revolution is equal to the light retention time of the normal hymaneye or less. The object is to avoid any apparent flicker to the eye inthe area illuminated. The lamp will light up the entire area within itssweep and the lighted area w ll appear to be continuously illuminatedalthough in fact any segment of the area is illuminated onlyintermittently. However, the speed of the traveling beam of light issuch that a light image is retained by the eye between cycles so thatthe eye is not aware of any intervening dark periods. The normal humaneye will not distinguish any flicker in an intermittent light sourcewhich flashes 30 or 40 times a second. In fact, it is said that the eyewill retain an image for a tenth of a second so that actually the devicemight be operated at a speed as low as revolutions per second. However,at this speed there is some chance for flicker and therefore a higherspeed, on the order of 30 to 40 revolutions per second, is recommended.Hence, the unit 10 should be rotated between 1800 and 2400 revolutionsper minute. This is independent of the angle of adjustment of the lampunit with respect to the axis 54. While the speed may vary vary, itshould be such that the time required for one revolution is on the orderof the light retention time of the normal human eye or less.

It will be noted that the drive shaft 26 and support 12 are providedwith passages 70 and 72 for electric wiring 74 to the lamp unit. If thewiring should produce an outof-balance condition, this can becompensated by counterbalancing the yoke.

The angle of the lamp unit with respect to the axis 54- may be adjustedby removiing the enclosing shell 60. This can be accomplished readily byunscrewing the fasteners 68 and applying sufiicient force to release thepress fitted marginal connection between the sections of the sphere.

What i claim as my invention is:

1. Apparatus for illuminating an area, comprising a single lamp unitadapted to emit a single beam of light when energized, a support forsaid lamp unit, means mounting said support for rotation about a fixedaxis through the center of gravity of said support so that said supportis in perfect dynamic balance when rotated, means mounting said lampunit on said support for rotation as a unit therewith and for pivotalmovement about a pivot axis at right angles to and intersecting the axisof rotation of said support, said second-mentioned means includingspaced, aligned trunnions lying on said pivot axis and respectivelylocated on opposite sides of saidlamp unit, means for locking said lampunit in selected positions of pivotal adjustment, and means for rotatingsaid support continuously at a high rate of speed such that the elapsedtime per revolution is on the order of the light retention time of thenormal human eye or less, the center of gravity of said lamp unit lyingon the intersection of the axis of rotation of said support andsaidpivot axis so that said lamp unit is in perfect dynamic balance whenrotated, said trunnions being spaced equal distances from saidintersection of said axes, and a spherical shell having a smooth outersurface completely enclosing and secured to said support for rotation asa unit therewith, the center of gravity of said shell lying on the axisof rotation of said support, said shell being circular in all sectionstaken at right angles to the axis of rotation and being symmetrical withrespect to said axis of rotation, said shell being transparent at leastin the region aligned with the beam of light from said lamp unit, saidshell being composed of two half-sections remo-v'ably recured togetheralong their margins, and the plane of said margins containing said axisof rotation.

2. Apparatus for illuminating an area as defined in claim 1, whereinsaid support is in the form of a yoke having legs on opposite sides ofsaid axis of rotation spaced equal distances therefrom, said legsstraddle said lamp unit, and said trunnions are respectively carried bysaid legs.

References Cited in the file of this patent UNITED STATES PATENTS1,417,457 Cook May 23, 1922 1,486,731 Cook Mar. 11, 1924 7 2,017,052Bartow Oct. 15, 1935 2,288,177 Bailey June 30, 1942 2,345,382 CramerMar. 28, 1944 2,553,061 Peckstein May 15, 1951

